Retroflex consonants, like other coronals, come in several varieties, depending on the shape of the tongue. The tongue may be flat, with the blade of the tongue (the top surface of the tongue near the tip) touching the roof of the mouth, as in Polishcz, sz, ż (rz), dż and Mandarinzh, ch, sh, r. This is termed laminal (laminal retroflex). Or they may be pronounced with the tip of the tongue, as in Hindi. This is termed apical (apical retroflex). Finally, the tongue may be curled back so that the underside touches the alveolar or pre-palatal region, as in many of the Dravidian languages. This is termed sub-apical (sub-apical retroflex).

The consonants commonly called postalveolar, or more precisely palato-alveolar, such as English sh and ch, as well as the alveolo-palatals, such as Mandarin q, j, x, are also pronounced in the postalveolar region. However, they differ from retroflex consonants in having an additional secondary articulation of palatalization. The consonants commonly called palatal are pronounced in the palatal region like the sub-apical retroflexes, but they touch the palate with the back of the tongue, not the tip. (That is, they are dorsal, or more precisely dorso-palatal, rather than coronal consonants.)

In other words, retroflex consonants include various types of coronal consonants articulated behind the alveolar ridge which do not have the secondary articulation of palatalization.

Occurrence

Although data is not precise, about 20 percent of the world's languages contain retroflex consonants of one sort or another. About half of these possess only retroflex continuants, with most of the rest having both stops and continuants. Retroflex consonants are relatively rare among European languages, occurring in Sardinian, in Sicilian, some southern Italian dialects such as Calabrian and Salentino, in Swedish and Norwegian (where a sequences of r plus a coronal consonant may be replaced by the coronal's retroflex equivalent, e.g. the name Martin would be pronounced [maʈin]. Also, this is sometimes done for several consonants in a row after an r - Hornstull is pronounced [hoɳʂʈul]). The retroflex approximant /ɻ/ is an allophone of the alveolar approximant /ɹ/ in many dialects of American English, particularly in the MidwesternUnited States. Polish and Russian possess retroflex sibilants, but no stops or liquids at this place of articulation. Retroflex consonants are largely absent from indigenous languages of the Americas with the exception of the extreme south of South America and an area in Southwestern US, as in Hopi and Papago. In African languages retroflex consonants are also very rare, reportedly occurring in a few Nilo-Saharan languages. In southwest Ethiopia, phonemically distinctive retroflex consonants are found in Bench and Sheko, two contiguous, but not closely related, Omotic languages.

Note: In the International Phonetic Alphabet, the symbols for retroflex consonants are typically the same as for the alveolar consonants, but with the addition of a right-facing hook to the bottom of the symbol. Some linguists restrict these symbols for the "true" retroflex consonants with sub-apical palatal articulation, and use the alveolar symbols with the obsolete IPA underdot symbol for an apical post-alveolar articulation: . Another solution, more in keeping with the official IPA, would be to use the rhotic diacritic for the apical retroflexes: . Laminal retroflexes, as in Polish and Russian, are often transcribed with a retraction diacritic, as [s̱], etc. Otherwise they are typically but inaccurately transcribed as if they were palato-alveolar, as *[ʃ], etc.